Planetary Transfer Gear Set With Direction-Dependent Gear Ratios

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Solution Overview

Problem

Actuation systems, such as screw-nut driven compressive loaded actuators, face inefficiencies due to differing torque and stroke time requirements for extension and retraction strokes, leading to oversizing of the system to accommodate maximum demands.

Innovation Solution

A variable gear ratio gear set system incorporating a planetary gear set with one-way clutches that change gear ratios based on the direction of input shaft rotation, allowing for optimized gear ratios for both extension and retraction strokes by altering torque transmission paths through the sun gear, carrier, and ring gear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the actuator and gear set are sized for the maximum torque and stroke time requirements, then the system can handle both extension and retraction strokes, but the system becomes oversized leading to increased weight and size

Engineering Contradiction:

Improveability to handle maximum torque requirementsVSAvoidactuator and gear set weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent applies a variable gear ratio mechanism that dynamically changes the gear ratio based on the stroke direction. During extension stroke, a first gear ratio provides high torque multiplication, while during retraction stroke, a second gear ratio provides different torque characteristics. This dynamic adaptation allows the actuator to be sized for the more demanding stroke while the variable gear ratio optimizes performance for both directions, reducing overall system size and weight compared to a fixed gear ratio system designed for maximum requirements.

Inventive Principle:

Principle #15Dynamics

2Ease of manufacture

If a fixed gear ratio is used, then the system structure is simpler, but the system cannot be optimized for different torque requirements of extension and retraction strokes

Engineering Contradiction:

Improvegear set structural simplicityVSAvoidability to handle different torque requirements

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent implements a variable gear ratio mechanism using one-way clutches that automatically switch between two gear ratios based on the direction of rotation. The mechanism includes a planetary gear set with one-way clutches that engage different gear paths during extension versus retraction strokes. This provides adaptability to different torque requirements while maintaining a relatively compact and manufacturable structure, balancing complexity with performance optimization.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The variable gear ratio mechanism operates automatically based on the direction of rotation without requiring external control signals. The one-way clutches self-engage or disengage depending on the rotational direction, allowing the system to automatically select the appropriate gear ratio for the current stroke type. This self-service operation reduces control system complexity while achieving adaptability to different torque requirements.

Inventive Principle:

Principle #25Self-service

3Productivity

If the gear ratio is optimized for one stroke direction, then performance is improved for that stroke, but the system cannot meet the requirements of the opposing stroke with the same optimization

Engineering Contradiction:

Improvestroke execution efficiencyVSAvoidability to meet opposing stroke requirements

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent employs a variable gear ratio mechanism that switches between a first gear ratio during extension stroke and a second gear ratio during retraction stroke. This dynamic adjustment allows each stroke direction to benefit from an optimized gear ratio tailored to its specific torque and speed requirements, thereby improving productivity for both strokes while maintaining reliability across the full range of operational demands.

Inventive Principle:

Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution enables the actuation system to be sized more efficiently, reducing weight and size by allowing separate optimization of gear ratios for each stroke, thereby improving performance and reducing material usage.

Implementation Method 1

a roller located between the ramp and the ring, such that during rotation of the first component in a first rotation direction urges the roller up the ramp to jam between the ramp and the ring preventing rotation of the first component relative to the second component

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS20240328482A1Variable gear ratio transfer gear set for actuation system

Publication Date: 2024.10.03 HAMILTON SUNDSTRAND CORP

AI summary

A variable gear ratio gear set system includes a planetary gear set including a sun gear locate at a central axis of rotation, a plurality of planet gears meshed with the sun gear and retained at a carrier, and a ring gear surrounding the plurality of planet gears and meshed therewith. An input shaft inputs rotational energy to the planetary gear set at a first rotational speed, and an output shaft outputs rotational energy from the planetary gear set at a second rotational speed. A plurality of one-way clutches are positioned in the gear set and are engageable such that the system has a first gear ratio when the input shaft is rotated in a first direction, and a second gear ratio when the input shaft is rotated in a second direction.